msem-instigator

Create an 8/8 blue Kraken creature token with hexproof.
Rerun (If you cast this from your hand, exile it as it resolves. Whenever a creature you control dies, you may cast this card from exile without paying its mana cost.)

At the beginning of your upkeep, if you control ten or more storied permanents, you win the game. (Enchantments and legendary permanents are storied.)

Escalate {2} (Pay this cost for each mode chosen beyond the first.)
Choose one or more —
• Search your library for a card, put it into your hand, then shuffle.
• Return target card from your graveyard to your hand.
• Add {B}{B}{G}{G}.

When Apprentice Summoner enters the battlefield, search your library for a creature card with mana value 1 or less, put it onto the battlefield, then shuffle.

At the beginning of your end step, put an encroachment counter on Approach of Old Lovi, then it deals X damage to any target and you gain X life, where X is the number of encroachment counters on Approach of Old Lovi.

As Aquatic Refuge enters the battlefield, you may tap an untapped creature you control. If you don't, Aquatic Refuge enters the battlefield tapped.
{T}: Add {W} or {U}.

Other creatures you control can't attack or block alone.

At the beginning of your upkeep, you may pay {1}{G/U}. If you do, proliferate. (Choose any number of permanents and/or players with counters on them, then give each another counter of each kind already there.)
At the beginning of your end step, you may pay {1}{G/U}. If you do, populate. (Create a token that's a copy of a creature token you control.)

Flying, lifelink
Improve {1}{W/B} ({1}{W/B}: Put a +1/+1 counter on this creature. This costs {1} more to activate for each +1/+1 counter on it. Improve only as a sorcery.)
Once each turn, when you gain life, you may have each opponent lose 2 life.

{1}{R}: Aravant Throatcutter and up to one other target Pirate or Rogue you control each get +1/+0 until end of turn.

Equipped creature gets +2/+2.
Whenever equipped creature deals combat damage to a player, exile cards from the top of their library until they exile a nonland card. You may cast that card without paying its mana cost.
Equip {2}

Vigilance
If another creature would die, exile it instead.
At the beginning of your upkeep, return each creature card exiled with Arbiter of Endless Summer to the battlefield under its owner's control.

Flying
When Arbiter of Silence enters the battlefield, exile all other creatures until Arbiter of Silence leaves the battlefield. (They return to the battlefield under their owners' control.)

Flash
Flying
As long as an opponent controls more creatures than you, Arbiter of the Scales gets +2/+2 and has first strike and lifelink.

Activated abilities of artifacts cost {2} more to activate.

{U}, Exile an instant or sorcery card from your graveyard: Draw a card, then discard a card.
{R}, Exile an instant or sorcery card from your graveyard: Arcane Harvesters deals 1 damage to any target.

Whenever Arcane Metalcrafter or another Wizard you control attacks, create a 1/1 colorless Construct artifact creature token that's tapped and attacking.
Whenever a Construct you control dies, Arcane Metalcrafter deals 1 damage to each opponent.

Whenever you cast an instant or sorcery spell, you may pay {1}. If you do, choose one—
• Draw a card, then discard a card.
• Tap target creature.
• Target creature gains flying until end of turn.
• Target player mills two cards.

Counter target spell. If that spell is countered this way, until the end of your next turn the next spell you cast that shares a type with it costs {X} less to cast, where X is the countered spell's mana value.

{T}: Add one mana of any color in your commander's color identity.

Counter target spell unless its controller pays {2}.
Reprise {3}{U} (As you cast an instant or sorcery spell, you may exile one card with reprise from your graveyard and pay its reprise cost. If you do, add its effects to that spell.)

If you casting a noncreature spell causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.
Cycling {2} ({2}, Discard this card: Draw a card.)

Wanderlust — When you cast this spell, you may copy it if you control four or more differently named lands.
Exile the top card of your library. Until the end of your next turn, you may play that card. Create a 1/1 Scout creature token that's all colors.

This spell costs {1} less to cast for each enchantment you control.
Flying, lifelink, trample
Disturb {6}{B}{B}. That spell costs {1} less to cast for each enchantment you control. (You may cast this card from your graveyard transformed for its disturb cost.)

Flying
Concord — When Archangel of Accord enters the battlefield, if there are four or more card types among permanents you control, destroy all other creatures.